Endovascular repairs are promising solutions for a minimally invasive treatment of Abdominal Aortic Aneurysms. This paper describes a new method for assisting surgeons in conducting endovascular procedures with a reduced X-rays exposure. An anatomical landmark-based registration between pre-operative 3D CT scan and transabdominal 2.5D Ultrasound images replaces the CT data in the intra-operative referential. A modified ICP algorithm computes the transformation between the internal surface of the aorta segmented from CT images and its position in ultrasound data. Magnetic tracking is performed to navigate a modified guidewire. The visualization module presents the location of the guidewire in multiplanar reformatted CT views and inside a 3D Model of the lumen. The relative position of the sensor is updated in real time from position data obtained from the magnetic tracking. We applied the method to an anatomical piece, and led an endovascular procedure with clinically satisfactory results.